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Abstract. The North Slope Eider Survey has been conducted for 10 consecutive years, 1992 to 2001. Survey techniques have remained constant, except that since1997 observations have been dictated directly into computers that were connected to an onboard GPS, giving precise coordinates for all observat...
| Main Authors: | , , , , , , , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.383.4937 http://www.arlis.org/docs/vol1/A/213375107/609897140-2001.pdf |
| Summary: | Abstract. The North Slope Eider Survey has been conducted for 10 consecutive years, 1992 to 2001. Survey techniques have remained constant, except that since1997 observations have been dictated directly into computers that were connected to an onboard GPS, giving precise coordinates for all observations. The survey pilot was the same person for all years, while the copilot/observer changed in 1997 and again in 2000. In 1998 the survey area was split into 11 geographical strata based on habitat features and the boundaries of the National Petroleum Reserve of Alaska, northeast planning area. Data were re-analyzed for all years using the new stratification, which slightly improved precision of the estimates and facilitated area-wise comparisons. The spring thaw was slightly later than average in 2001, and sea duck breeding phenology was delayed a few days. The 2001 breeding index for spectacled eiders was 7,370. This is slightly above the long-term average of 7,072,but there is still a non-significant downward trend (annual growth rate = 0.982). The King eider index was 17,031, which is the highest on record, well above the long-term average of 12,913, and continued the non-significant increasing trend (annual growth rate = 1.031). However, we believe the king eider index was inflated this year by the presence of transient birds, as suggested by unusually high numbers of paired and flocked birds in our phenology reference area early in the survey period, which dropped off rapidly thereafter. Significant long term increases were noted for arctic terns |
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